So, this is probably going to sound ridiculously overpowered, but how about an ammo that disables any part it hits for a very short time?
Guns can't fire, Engines stop providing thrust, the and the Balloon gets them stuck at where they are height-wise. Probably for a massive decrease in damage per shot, admittedly, and maybe a range reduction because can you imagine this on Flamers? There would be a new meta. And it would be fire.
This gives me a slightly less OP idea:
EMS - ElectroMagnetic Shock ammo.
-100% damage
-100% fire chance
+X% chance to apply a variable number of "shock stacks" to the target.
Number of potential stacks applied would be based on the damage dealt by the weapon, and extremely low-damage weapons could have slightly reduced chance to apply a stack in addition to only applying one per hit (to prevent the Flamer or Gat from being too easily abused).
Being shocked would put items on cooldown for the duration of the shock effect (preferably below 2s even with maximum stacks), and engines and weapons would have secondary effects. Engines would provide 0 thrust while shocked, and light weapons would be unable to fire, while heavy weapons would be prevented from both firing and turning. Both can be reloaded normally.
The Flamer's low damage would mean a small probability of causing a stack, as well as only one stack per shot, but the rapid fire and the wide AoE (unaffected by the ammo) would help to keep it viable with this ammo. Likewise, EMS Gats would be relatively minimal effect per hit, but could be used to put large portions of the target ship on cooldown and stall repairs for a couple of seconds at a critical moment.
Lack of damage means you're relying on bifectas/trifectas pairing with the weapon, making it a great utility ammo, but less viable for direct combat.